Motorola Surfboard 6121 question

Solution
It depends on the router WAN port that you connect it to -- if it is gigabit it will be blue, otherwise it will be amber. Many routers that have gigabit LAN ports still only have Fast Ethernet (100Mbps) WAN ports.
I think I understand what you're saying. I'm using an older Linksys wrt54g router so that's probably my issue. I'm just happy to return the rented one from Comcast.